1. Field of the Invention
The present invention relates to an engaging apparatus of a printing cylinder cleaning unit and, more particularly, to an engaging apparatus of a printing cylinder cleaning unit which is suited to a case where blanket cylinder of a printing machine takes such a movable structure as to alternately contact an adjacent impression drum and other blanket cylinders.
The cleaning device of the printing cylinder cleans the cylinder surface by making a rotary brush and a cleaning sheet wetted with a cleaning liquid contact with the printing cylinder. For this reason, the cleaning device is contact/separate-driven by the engaging apparatus so that the cleaning device contacts a cylinder drum for a cleaning time but separates from the cylinder drum for a non-cleaning time.
The conventional engaging apparatus includes, as illustrated in FIG. 5, contact/separate operating swing arms 2, disposed at both ends of a cleaning device unit 1, for fixedly holding the unit 1. This swing arm 2 is swingably supported on an unillustrated fixed plate through a rotary support shaft 3. At the same time, an expansion rod of an air cylinder similarly mounted on the fixed plate is connected to this swing arm 2. The swing arm 2 can be thereby swingably driven about the rotary support shaft 3. Then, the swing arm 2 is fitted with a stopper rod 6, and a stopper plate 7 is mounted on the unillustrated fixed plate so that a cleaning portion of a brush or the like of the cleaning device unit 1 properly contacts a cylinder drum 5. With this arrangement, when swinging the swing arm 2 towards the cylinder drum 5 for the purpose of a cleaning operation, the stopper rod 6 impinges on the stopper plate 7, thus effecting a positioning process. In this state, the cleaning portion of the brush or the like is set to contact the cylinder drum 5 at a proper contact pressure. Further, for adjusting the contact pressure, the stopper rod 6 is equipped with an adjusting bolt 8, whereby a contact pressure is arbitrarily settable by adjusting the bolt 8.
A blanket drum to be cleaned rotationally contacts an adjacent impression drum or blanket drum. In the case of a unit equipped with a half deck to change the contact object depending on a print mode, however, the contact object of the blanket drum changes to any one of the impression drum and other blanket drums. In the printing cylinder having a plurality of contact objects during the printing process described above, a rotary shaft core position is varied. It is therefore required that the cleaning device adjusts the position of the engaging apparatus every time the contact changeover is effected. To be specific, when changing the rotational center of the cylinder drum 5, the relative distance to the cleaning device unit 1 varies. This leads to such a problem that the adjusting operation by the above-described adjusting bolt 8 is required each time.